1. Field of the Invention
The present invention relates to an apparatus and method for examining wafers, and more particularly, to an apparatus and method for examining wafers, by which the operator can easily perceive the completion of the wafer examining process steps. The wafers are held until their examination is completed, whereby the wafers are prevented from being broken due to carelessness of the operator while the operator works by the system.
2. Description of the Related Art
FIG. 1 shows a conventional apparatus for examining wafers. Referring to FIG. 1, first and second locators 9A and 9B, and an aligner 6 are disposed around a scanning chamber 7. Wafer cassettes 10 are loaded one-by-one on the first and second locators 9A and 9B. The aligner 6 aligns the flat zone of the wafer 5 picked up from the wafer cassette 10 by a robot arm 4.
In the meantime, a system controller 2, electrically connected to the scanning chamber 7, displays the resultant data of an examined wafer on a monitor 8. When a start switch 1 is operated, the system controller 2 operates the robot arm 4 according to a preset program by means of a robot controller 3.
Following is a brief description of a process for examining the wafers in the wafer cassette 10 by the conventional apparatus. When an operator turns on the start switch 1 after loading a wafer cassette 10 on the first locator 9A, the system controller 2 outputs an operational control signal to the robot controller 3, so that the robot arm 4 picks up one of the wafers in the wafer cassette 10 and then carries the picked-up wafer to the aligner 6. The aligner 6 aligns the flat zone of the carried wafer. The wafer is moved to the scanning chamber 7 where the wafer is scanned to determine whether or not particles remain on the wafer. The resultant data of the scanned wafer are inputted into the system controller 2 and then displayed on the monitor 8 by the system controller 2.
After the resultant data are displayed on the monitor 8, the robot arm 4 carries the scanned wafer to the wafer cassette 10 loaded on the second locator 9B.
In the conventional apparatus for examining wafers, since the wafer is moved to the wafer cassette 10 loaded on the second locator 9B after the resultant data are displayed on the monitor 8, the operator can erroneously pick up the wafer cassette 10 from the second locator 9B in order to carry the wafer cassette 10 to another area before all of the wafers in the wafer cassette 10 are examined. More specifically, when the operator picks up the wafer cassette 10 from the second locator 9B, after he confirms the resultant data of the last wafer displayed on the monitor 8 but before the last wafer from the first locater 9A is completely carried to the wafer cassette 10 on the second locator 9B, the last carried wafer may collide with the wafer cassette 10 or other structures. Such collisions may break the wafer, thereby degrading the yield of the semiconductor devices.